1. Technical Field
The present invention relates to an illuminator that provides illumination to a liquid-crystal light valve or other light modulator, and to a projector incorporating the same.
2. Related Art
As a first projector, there is an arrangement that the two polarized light components exiting from the polarization beam splitter opposed to a light-source lamp, are focused to one end of a rod integrator so that one of the polarized light components of the light exiting at the other end thereof, can pass a periodic point at which a retardation film is arranged, thereby obtaining a uniform, single polarized light component of illumination light (see JP-A-2000-56266, FIG. 1).
As a second projector, there is an arrangement that the source light emitting from a light-source lamp, is focused to one end of a rod integrator so that the light exiting at the other end is polarization-converted by a polarization converter made by a polarization beam splitter or the like, thereby obtaining a uniform, single polarized light component of illumination light (see JP-A-2000-56266, FIG. 14).
As a third projector, there is an arrangement that the source light of from a light-source lamp is focused to one end of a rod integrator through an aperture provided in the center of a reflection mirror, thereby obtaining a uniform, single polarized light component of illumination light through a polarization separation element provided on the other end thereof (see JP A 2003-202523). In this case, when turning back the reflection light from the polarization separation element by a reflection mirror, it is passed through the polarization separation element by changing the direction of polarization through use of a wavelength plate provided on the optical path.
However, in the first and second projectors, illumination light is made uniform by the rod integrator. For this reason, the target of uniformization cannot be achieved without increasing the length of the rod integrator, which tends to increase the size of the illuminator and its surrounding. Moreover, the first projector requires a retardation film arranged in a stripe form at a conjugate point to a light-incident end of the integrator. This makes it difficult to fabricate the illuminator and its surrounding, resulting in cost increase.
Meanwhile, in the third projector, uniformization is not sufficiently achieved for a nearly half component which first passed the polarization separation element.